Tbh I didn't ****in know what category this would go in but whatever.

I'm a guitarist (electric) and have really cold hands. Not like "slightly chilly, if I warm up for 15 minutes I'm fine" cold hands.
But like "have to put on a wool sweater and warm up for 45 minutes and I'm still f'ing freezing and sometimes have to put on finger gloves" cold hands.

It's really upsetting me and getting in the way of my playing and sometimes it's even painful... I also go to a music school where I get guitar lessons 4 times a week so it's very inconvenient to say the least.

Since I'm a girl the only reasonable explanation I can come up with is that my thyroid is ****ed up, but thats it...

Has anyone here had a problem like this (minus the thyroid thing)?? And what do you guys do to warm up if you have really cold hands??
That sounds like a circulatory issue. I'd suggest going to see a doctor to see what the hell is going on. Godd luck